(a) Field of the Invention
The present invention relates to a method of transferring graphene.
(b) Description of the Related Art
In order to analyze material characteristics and electrical characteristics of a large-area graphene grown on metal, a process of moving the graphene to an insulating film or an insulating substrate is essential. To this end, a method of growing graphene, etching metal, and transferring the graphene in a floating state to a target substrate is commonly used.
Korean Patent Laid-Open Publication No. 2012-0137048 (Dec. 20, 2012) discloses a graphene transfer method.
In this graphene transfer method, since a graphene film consisting of one atomic layer is easily broken by a small surrounding force, a method of forming a support surface, such as polymethyl methacrylate (hereinafter referred to as “PMMA”), by coating, moving the support surface to a desired substrate, and finally removing the PMMA is being used in order to obtain a large-area graphene. PMMA that is not fully removed in this process deteriorates the electrical characteristics of the grapheme, which become a major cause of not realizing theoretically expected electrical characteristics and effects even in devices using the grapheme. In order to solve the problems, a variety of washing methods and methods of removing PMMA residues through heat treatment after transfer have been used, but the creation of PMMA residues cannot be perfectly prevented.
Furthermore, active researches have recently been carried out on materials having new characteristics obtained by combining a self-assembled monolayer (SAM) and graphene. In the case of the functional graphenes, there have been reports on changing the work function of the graphene, controlling a doping concentration, or improving the mobility of charges. However, in the graphenes, basically, a SAM is deposited on a substrate and graphene is transferred to a surface of the substrate on which PMMS is supported. Accordingly, there are problems in that lots of residues are present at the interface of the graphene and the SAM and in a surface of the graphene, and the removal of the residues using an organic solvent or heat treatment is greatly limited.